Modern eye tracking devices allow determining and recording gaze position with high accuracy. To achieve this, the reflected light from infrared light diodes on the eyes and the position of the pupil is recorded by a camera. From these data, gaze position can be calculated. In our lab we have a Tobii Eye tracking system (Tobii 1750).

The measurement of gaze position is of great interest in cognitive science research. In some complex tasks such as visual search, problem solving or navigation, the path of eye movements themselves is scrutinized by the researcher. In other tasks, however, such as, for example, the presentation of stimuli in specific positions of the visual field, eye movements are only recorded to monitor participants' compliance with fixation instructions. In interactive studies, stimulus presentation is even coordinated depending on eye movements. For example, in a computer-aided translation tasks, translation suggestions are presented above the word fixated by the participant.